This application represents a request for support of additional years to continue and expand the presently functioning Clinical Cancer Radiation Therapy Research Center. The present Cancer Research Center project has produced an environment whereby there is an integration of the activities of the clinical oncologists and the cancer biologists directed towards the objectives of improved control and cure of cancer in patients. The objectives of this Center project have been pursued successfully for the past four years with an increasing level of effort and productivity through which the Center has acquired new laboratory space and facilities and has recruited young, enthusiastic and aggressive new staff. Thus, there is opportunity and need for further support for the enlarged scope of projects and expanded efforts into cancer research and therapy. The major research areas undergoing expansion from the current level are: (a) the kinetics of tumor and normal cell populations and their influence on tumor growth; (b) the mechanisms of action and effects of X-radiation, chemotherapy and combination therapy on normal and malignant tissues; (c) basic concepts of tumor immunology; and (d) the mechanisms of cell differentiation, both normal and abnormal. Investigations will be directed at a cell and tissue level towards quantitation and evaluation of the kinetics of tumor and normal cell populations using relevant functional end points such as proliferative capacity, cell differentiation and tumor cure or normal tissue damage. The observation and results obtained at the preclinical level are directed towards an understanding of the mechanisms of tumor cure and tumor failure for direct application and development of experimental treatment regimens as pilot studies.